I played around quite a bit with this pen...hoping to find SOMETHING that i can see eaisily...just love it...however I don't use it on gift quilts...never know when the quilt will get left in a car or moved across country in the dead of winter..those lines will return.
I have read that if you use starch the lines don't wash out, otherwise they do wash out so for now I use the pen for marking in the margins only.